A controller circuit board thermal fuse and manufacturing method thereof

Abstract

The present invention discloses a controller circuit board thermal fuse and a manufacturing method thereof, which relates to the technical field of fuses, and includes an insulating seat, a spring, a conductive sheet and an upper cover, wherein: the conductive sheet and the spring are arranged in the insulating seat in sequence up and down in a state where the force is kept in the middle, and the upper cover is buckled on the insulating seat and transmits the extrusion force to the conductive sheet and the spring, so that the spring is compressed and the conductive sheet is in a welding position, when the current of the circuit board is too large, the tin of the circuit board pad melts, and the conductive sheet on the thermal fuse pops open under the action of the spring elastic force, the circuit board circuit is disconnected, and circuit protection is achieved. The present invention solves the problems of the existing thermal fuse occupying too large a circuit board area, requiring shaping to produce the required internal stress after welding with the circuit board, expensive detection equipment, and easy damage to the circuit board due to shaping, by providing a thermal fuse with a completely new structure.

Description

Technical Field

[0001] The invention relates to the technical field of fuses, and in particular to a controller circuit board thermal fuse and a manufacturing method thereof. Background Art

[0002] At present, thermal fuses are often used in controller circuit boards. When the controller is in use, when the circuit board current is too large, the tin on the corresponding pad of the thermal fuse spring melts, and the fuse spring (or conductive sheet) pops open under the action of internal stress (or spring force), disconnecting the circuit to protect the product.

[0003] After the existing thermal fuse is reflowed with the circuit board, it needs to be pressed and shaped to make the thermal fuse spring produce internal stress (or transfer the elastic force of the spring to the pad). For example, the Chinese utility model patent with the patent authorization announcement number CN2342462Y discloses a spring-open thermal fuse, which is cut and formed by metal wire, has two pins and an elastic section, and the elastic section is connected between the two pins and wound to form a coil. When the two pins are subjected to reverse force and then soldered to the circuit contact, because the elastic section has elastic force, if the circuit is passed with current, when the temperature of the circuit substrate rises to the melting temperature of the solder, the tin surface will soften due to melting, and the pin will be spring-opened by the elastic section to achieve the protection function. In this technical solution, the thermal fuse needs to be press-fitted and shaped during reflow soldering until it fits the circuit board as a whole, so as to avoid the thermal fuse occupying too much vertical space on the circuit board and affecting the subsequent assembly. However, the press-fit shaping operation is prone to damage the circuit board, inadequate shaping or over-shaping. After the shaping is completed, corresponding equipment is required to detect the shaping results, which requires a large investment.

[0004] In addition, the existing fuses also have the problem of large size. For example, the patent authorization number is CN209912829U, which includes a shell, a fuse, a heat expansion member and a cover. The fuse includes a first electrode sheet, a second electrode sheet and a fuse. The fuse is connected between the first electrode sheet and the second electrode sheet. The first electrode sheet is fixedly connected to the first slot body. The fuse can be automatically disconnected when the power supply current is abnormal. The thermal fuse in this technical solution has a large overall structure, especially the two protruding electrode sheets, which occupy a large space and are not friendly to the layout of the circuit board.

[0005] Based on the above problems, the present invention designs a controller circuit board thermal fuse and a manufacturing method thereof to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a controller circuit board thermal fuse and a manufacturing method thereof. The thermal fuse is small in size, simple to assemble and does not require shaping after welding, has a simple process and low cost.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A controller circuit board thermal fuse comprises an insulating seat, a spring, a conductive sheet and an upper cover, wherein:

[0009] The conductive sheet and the spring are arranged in the insulating seat in sequence up and down in a state of keeping the force centered. The upper cover is buckled on the insulating seat and transmits the extrusion force to the conductive sheet and the spring, so that the spring is compressed and the conductive sheet is in a welding position.

[0010] Furthermore, the conductive sheet includes three states: a pre-installed state, a press-fitted state, and a melted and popped-open state.

[0011] Furthermore, a spring limiting groove is provided on the insulating seat, and the spring is located in the spring limiting groove;

[0012] The insulating seat is also provided with a spring limiting structure to limit the spring as a whole to maintain a centered state.

[0013] Furthermore, a conductive sheet limiting structure is provided on the insulating seat, so that the conductive sheet is positioned on the insulating seat when it is pre-installed and melted and popped open.

[0014] Furthermore, a conductive sheet guide structure is provided on the insulating seat to ensure that the conductive sheet remains centered when it is pre-installed, pressed into place, or melted and ejected.

[0015] Furthermore, the conductive sheet guide structure includes an upper guide portion and a lower guide portion, wherein: the upper guide portion allows the conductive sheet to remain centered when it is pre-installed, melted and popped open; the lower guide portion allows the conductive sheet to remain centered when it is pressed into place.

[0016] Furthermore, an end surface of the upper cover facing away from the insulating seat is provided with a suction plane for suction by a vacuum suction nozzle.

[0017] Furthermore, a detection window is provided on the insulating seat.

[0018] A manufacturing method for manufacturing a controller circuit board thermal fuse, the method comprising:

[0019] Step 1), injection molding of the insulating seat;

[0020] Step 2), put the spring into the spring limit groove;

[0021] Step 3), pre-installing the conductive sheet: the conductive sheet is positioned based on the conductive sheet limiting structure and the upper end guide part, centered on the insulating seat, and the spring is kept in a pre-compression state;

[0022] Step 4) Press-fit the conductive sheet into place: The upper cover is buckled onto the plastic base, the pre-installed conductive sheet is pressed into place, and the spring is further compressed. At the same time, the conductive sheet is centered on the insulating seat based on the action of the lower end guide part;

[0023] Step 5), soldering the conductive sheet pins to the circuit board to achieve soldering of the thermal fuse to the circuit board;

[0024] Step 6) Remove the upper cover, the conductive sheet and the spring lose the squeezing effect of the upper cover, and the spring force is now transmitted to the circuit board pad.

[0025] Furthermore, when the current of the circuit board is too large, the tin of the circuit board pad melts, and the conductive sheet on the thermal fuse pops open under the action of the spring force, the circuit board circuit is disconnected, and circuit protection is achieved.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) In the present invention, a controller circuit board thermal fuse with a completely new structure is provided. After the thermal fuse is welded and assembled with the circuit board, the upper cover is removed, and only the conductive sheet, the insulating seat and the spring are retained. The overall volume of the thermal fuse is small, which is convenient for arrangement on the circuit board. Moreover, based on the provided thermal fuse structure, the thermal fuse conductive sheet can be made of materials with high conductivity, such as brass, copper, etc., to further reduce the volume, so as to facilitate its arrangement on the circuit board. In addition, based on the structure of the spring force to realize melting and opening, the conductive sheet can be made of inelastic materials, such as ordinary copper, to further reduce the cost.

[0028] (2) After the upper cover of the thermal fuse installed on the circuit board is removed, the spring force is transmitted to the pad to achieve thermal protection without the need for post-process shaping. This is not only less likely to damage the circuit board, but also saves related press-fitting and equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the insulating seat in the present invention;

[0030] Figure 2 It is a schematic diagram showing the structure of the spring installed on the insulating seat in the present invention;

[0031] Figure 3 It is a schematic diagram showing the structure of the conductive sheet installed on the insulating seat in the present invention;

[0032] Figure 4 Schematic diagram of the structure of the conductive sheet limiting structure in the present invention (the conductive sheet is in a pre-installed state at this time);

[0033] Figure 5 It is a schematic structural diagram showing the guiding portion at the upper end of the conductive sheet in the present invention;

[0034] Figure 6 It is a schematic diagram showing the structure of the upper cover buckled on the insulating seat in the present invention;

[0035] Figure 7 Schematic diagram of the structure of the guide portion at the lower end of the conductive sheet in the present invention (the conductive sheet is in a press-fitted state at this time);

[0036] Figure 8 It is a schematic diagram showing the structure of a thermal fuse welded on a circuit board in the present invention;

[0037] Fig. 9 It is a cross-sectional view showing the thermal fuse welded on the circuit board after the upper cover is removed in the present invention;

[0038] Fig.10 The figure is a schematic diagram showing the state of the thermal fuse after it melts and pops open according to the present invention.

[0039] In the figure: 1. Insulating seat; 2. Spring; 3. Conductive sheet; 4. Upper cover; 5. Spring limiting groove; 6. Spring limiting structure; 7. Conductive sheet limiting structure; 8. Conductive sheet guiding structure; 9. Upper end guiding part; 10. Lower end guiding part;

[0040] a. Thermal fuse; b. Circuit board; b1. Circuit board pad. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0042] A controller circuit board thermal fuse comprises an insulating seat 1, a spring 2, a conductive sheet 3 and an upper cover 4. The conductive sheet 3 and the spring 2 are arranged in the insulating seat 1 in sequence from top to bottom with the force centered. The upper cover 4 is buckled on the insulating seat 1 and transmits the extrusion force to the conductive sheet 3 and the spring 2, so that the spring 2 is compressed and the conductive sheet 3 is in a welding position. When welding, the pins of the conductive sheet 3 are welded to the pads of the circuit board.

[0043] The connection and position relationship of each structure of the thermal fuse are described in detail as follows:

[0044] First, it should be noted that the thermal fuse of the present application includes three states during installation and use, namely: a pre-installed state, a press-fitted state, and a melted and popped-open state.

[0045] like Figure 1 As shown, the insulating seat 1 includes a bottom support portion and an upper mounting portion, and the upper mounting portion is located at both sides of the top of the bottom support portion. Preferably, the insulating seat 1 can be made of insulating materials such as plastic.

[0046] Among them, a spring limiting groove 5 is opened at the center position of the top of the bottom support part. Preferably, the spring limiting groove 5 is a circular groove structure, such as Figure 2 As shown, the spring 2 is installed in the spring limiting groove 5. The insulating seat 1 is also provided with a spring limiting structure 6, which can adopt a cylindrical limiting rod structure, and the outer diameter of the limiting rod matches the inner diameter of the spring 2. When installed, the spring 2 is sleeved on the limiting periphery to limit the spring 2 to remain in the center as a whole, thereby ensuring that the spring 2 does not deviate as a whole during compression or release of elastic force.

[0047] In addition, a detection window 12 is also provided on the insulating seat 1. The detection window 12 is provided to facilitate ensuring whether the position of the detection spring 2 is correct when the thermal fuse is assembled.

[0048] The conductive sheet 3 is installed at the center of the insulating seat 1 , and is positioned and guided by the upper mounting portion on the insulating seat 1 , and exerts a pre-compression effect on the spring 2 .

[0049] Specifically, the conductive sheet 3 as a whole is composed of a middle portion, two connecting portions at both ends, and two solder feet at both ends. Among them, the middle portion maintains a top plane structure to provide an extrusion plane for the upper cover 4 to be extruded, and the two ends of the middle portion are connected to the solder feet through the connecting portions. The two connecting portions at both ends are arc-shaped transition structures, and the solder feet at both ends maintain the same plane structure as the middle portion to provide a soldering plane when soldering on the circuit board later.

[0050] In order to position the conductive sheet 3 and keep the initial centered state in any state of pre-installation, press-installation and ejection. A conductive sheet limiting structure 7 and a conductive sheet guiding structure 8 are provided on the insulating seat 1. Among them, the conductive sheet limiting structure 7 is used to position the conductive sheet 3 on the insulating seat 1 when it is pre-installed and melted and ejected; the conductive sheet guiding structure 8 is used to keep the conductive sheet 3 in a centered state when it is pre-installed, pressed into place and melted and ejected. And further, the conductive sheet guiding structure 8 includes an upper guide part 9 and a lower guide part 10, wherein: the upper guide part 9 keeps the conductive sheet 3 in a centered state when it is pre-installed, melted and ejected; the lower guide part 10 keeps the conductive sheet 3 in a centered state when it is press-installed into place.

[0051] In a possible embodiment, the conductive sheet limiting structure 7, such as Figure 4 As shown, limiting surfaces are provided at the four corners of the upper mounting portion on the insulating seat 1 corresponding to the welding feet of the conductive sheet 3. The limiting surfaces are kept consistent with the plane of the welding feet of the conductive sheet 3. When the conductive sheet 3 is installed, the upper plane of the welding feet is positioned by the limiting surfaces to fix the conductive sheet 3.

[0052] The upper guide portion 9 of the conductive sheet guide structure 8 is as follows Figure 5As shown, guide slopes are provided at the four corners corresponding to the upper mounting portion of the insulating seat 1 and the arc-shaped mounting portion of the conductive sheet 3. The guide slopes keep the conductive sheet 3 in the center position on the insulating seat 1, and play a centering guiding role when the conductive sheet 3 is pre-installed and ejected.

[0053] When the conductive sheet 3 and the spring 2 are both installed in place on the insulating seat 1, the thermal fuse is in a pre-installed state.

[0054] Then the pre-installed state is changed to the pressed-in state, and this change process needs to be realized with the help of the upper cover 4.

[0055] The upper cover 4 is buckled on the insulating seat 1, and the buckling method can ensure that the upper cover 4 can be removed from the insulating seat 1 later. Figure 6 As shown. Preferably, the upper cover 4 can be made of insulating materials such as plastic. The upper cover 4 includes a middle suction plane 11 and buckling surfaces located at the four corners of the middle suction plane 11. The top of the middle suction plane 11 can be sucked by a vacuum nozzle.

[0056] The buckling structure of the upper cover 4 and the insulating seat 1 can be as follows in a possible embodiment: another buckling surface that buckles with the upper cover 4 is provided at the four corners of the outer side of the upper end mounting portion on the insulating seat 1, and the buckling of the upper cover 4 and the insulating seat 1 is achieved through the interaction force of the two buckling surfaces.

[0057] After the upper cover 4 is buckled onto the insulating seat 1, the conductive sheet 3 is pressed into place to detach from the upper mounting portion, and the conductive sheet 3 further squeezes the spring 2, and the spring 2 further accumulates elastic potential energy; the welding feet on the conductive sheet 3 are pressed into place by the upper cover 4 to the welding position, and at the same time, the conductive sheet 3 is guided in the center by the upper and lower guide portions 10 of the insulating seat 1.

[0058] The lower end guide portion 10 is formed on the lower end support portion of the insulating seat 1, and guide slopes are provided on both sides of the lower end support portion. Figure 7 As shown, when the thermal fuse is pressed into place, the guiding slope keeps the conductive sheet 3 in a state of centering the force. At this time, the thermal fuse is in a state of being pressed into place.

[0059] When the thermal fuse is in the pressed-in state, the thermal fuse can be welded to the circuit board using welding technology. Figure 8 As shown, after the welding is completed, the upper cover 4 is removed from the insulating seat 1, as shown in FIG. Fig. 9 As shown, after the upper cover 4 is removed, the squeezing force of the upper cover 4 on the conductive sheet 3 and the spring 2 disappears. After that, the thermal fuse remains in this state on the circuit board until it melts and pops open to play a protective role. The thermal fuse when it melts and pops open is in the melted and popped open state.

[0060] In the melted state, Fig.10As shown, the conductive sheet 3 is bounced open by the elastic force of the spring 2 and returns to the initial pre-stressed state. At this time, the upper end guide part 9 still plays a central guiding role for the conductive sheet 3.

[0061] In addition, based on the structure of the controller circuit board thermal fuse, the present application also provides a manufacturing method for manufacturing the controller circuit board thermal fuse, the method comprising:

[0062] Step 1), plastic insulating seat 1 is integrally injection molded (such as Figure 1 shown);

[0063] Step 2), put the spring 2 into the spring limiting groove 5, and put it on the outer periphery of the spring limiting structure 6 in the shape of a round rod to ensure that the spring 2 does not deviate (such as Figure 2 shown);

[0064] Step 3), pre-install the conductive sheet 3 (such as Figure 3 As shown): The conductive sheet 3 is positioned based on the conductive sheet limiting structure 7 with a limiting surface and the upper end guide portion 9 with a guiding slope, centered on the insulating seat 1, and the spring 2 is kept in a pre-compression state (as shown in FIG. Figure 4-5 shown);

[0065] Step 4), press the conductive sheet 3 into place: the upper cover 4 is buckled onto the plastic base (such as Figure 6 As shown), the pre-installed conductive sheet 3 is pressed into place, and the spring 2 is further compressed. At the same time, the conductive sheet 3 is centered on the insulating seat 1 based on the action of the lower end guide portion 10 (as shown Figure 7 wherein the installation operation of the upper cover 4 is achieved by sucking the upper cover 4 at the top of the suction plane 11 by the vacuum nozzle.

[0066] Step 5), solder the pins of the conductive sheet 3 to the pads of the circuit board to achieve the welding of the thermal fuse and the circuit board; the welding is performed by tin soldering. (such as Figure 8 (shown)

[0067] Step 6), remove the upper cover 4, the conductive sheet 3 and the spring 2 lose the squeezing effect of the upper cover 4, and the conductive sheet 3 is fixed by the welding point, maintaining the compression state of the spring 2, and the elastic force of the spring 2 is transmitted to the pad of the circuit board. (As shown in Fig. 9 (shown)

[0068] After the thermal fuse and the circuit board are welded, the upper cover is removed and a simple continuity test (such as the ICT test commonly used in circuit boards) can be used to determine the state of the thermal fuse, which not only facilitates the detection of the state of the thermal fuse, but also reduces the difficulty of the detection process.

[0069] After the above steps 1) to 6) are completed, the thermal fuse is assembled. After the assembly is completed, no post-process shaping is required and the circuit board will not be damaged.

[0070] In subsequent work, when the circuit board current is too large, the tin on the circuit board pad melts, such as Fig.10 As shown, the conductive sheet 3 on the thermal fuse is opened under the action of the spring force, and the circuit board circuit is disconnected, thereby achieving circuit protection.

[0071] In summary, the present invention designs a thermal fuse with a brand-new structure, which can solve the pain points of existing thermal fuses on the market, that is, it solves the problems that the existing thermal fuses occupy too much circuit board area, need to be shaped after welding with the circuit board to generate the required internal stress, the detection equipment is expensive, and the shaping is easy to damage the circuit board.

[0072] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A controller circuit board thermal fuse, characterized in that: The invention comprises an insulating seat (1), a spring (2), a conductive sheet (3) and an upper cover (4), wherein the conductive sheet (3) and the spring (2) are arranged in sequence in the insulating seat (1) in a state where the acting force is centered, and the upper cover (4) is buckled onto the insulating seat (1) and transmits a squeezing force to the conductive sheet (3) and the spring (2), so that the spring (2) is compressed and the conductive sheet (3) is in a welding position; The conductive sheet (3) comprises three states: a pre-installed state, a pressed-in state and a melted and popped-open state; The insulating seat (1) is provided with a spring limiting groove (5), and the spring (2) is located in the spring limiting groove (5); The insulating seat (1) is also provided with a spring limiting structure (6) to limit the spring (2) to remain in a centered state as a whole; The insulating seat (1) is provided with a conductive sheet limiting structure (7) so that the conductive sheet (3) is positioned on the insulating seat (1) when it is pre-installed and melted and popped open; The insulating seat (1) is also provided with a conductive sheet guide structure (8) to play a central guiding role when the conductive sheet (3) is pre-installed, pressed into place, or melted and ejected; The conductive sheet guide structure (8) comprises an upper guide portion (9) and a lower guide portion (10), wherein: the upper guide portion (9) enables the conductive sheet (3) to remain in a centered state when it is pre-installed, melted and popped open; and the lower guide portion (10) enables the conductive sheet (3) to remain in a centered state when it is pressed into place; The end surface of the upper cover (4) facing away from the insulating seat (1) is provided with a suction plane for suction by a vacuum suction nozzle; The insulating seat (1) is also provided with a detection window; For manufacturing the controller circuit board thermal fuse, the method comprises: step 1), injection molding of the insulating seat (1); Step 2), place the spring (2) into the spring limiting groove (5); Step 3), pre-installing the conductive sheet (3): the conductive sheet (3) is positioned and centered on the insulating seat (1) based on the conductive sheet limiting structure (7) and the upper end guide part (9), and the spring (2) is kept in a pre-compression state; Step 4), press-fit the conductive sheet (3) into place: the upper cover (4) is buckled onto the plastic base, the pre-installed conductive sheet (3) is pressed into place, and the spring (2) is further compressed, and at the same time, the conductive sheet (3) is centered on the insulating seat (1) based on the action of the lower end guide part (10); Step 5), soldering the pins of the conductive sheet (3) to the circuit board to achieve soldering of the thermal fuse to the circuit board; Step 6), remove the upper cover (4), the conductive sheet (3) and the spring (2) lose the squeezing effect of the upper cover (4), and the elastic force of the spring (2) is transmitted to the pad of the circuit board; When the current of the circuit board is too large, the tin of the circuit board soldering pad melts, and the conductive sheet (3) on the thermal fuse pops open under the elastic force of the spring (2), and the circuit board circuit is disconnected, thereby achieving circuit protection.

Images